Bridge decision due; no blame laid for collapse

The Sutton bridge was destroyed in a flood  last year. Photo: ODT
The Sutton bridge was destroyed in a flood last year. Photo: ODT
The Dunedin City Council will decide today whether to commit to a $2 million "new" heritage bridge at Sutton.

But a review of the collapse of the old 19th-century bridge during last July’s floods has stopped short of blaming contractors or their scaffolding for the damage.

The single-lane cable suspension bridge, which spanned the Taieri River on Sutton-Mount Ross Rd, had stood since 1875 but was undergoing strengthening work when the July floods hit.

Local residents claim debris caught in the scaffolding had contributed to the bridge’s demise, but a report for today’s  DCC infrastructure services and networks committee meeting says otherwise.

The report, by council transport group manager Richard Saunders, says a review  found "no definitive reason for the collapse of the bridge".

"Council will not be pursuing costs from either the professional services contractor or the physical works contractor."

Contacted on Friday,  Mr Saunders said while scaffolding was on the bridge at the time it collapsed, "it was there for appropriate reasons to finish off the remaining work, to get the original project completed".

"That may have contributed to [the collapse], but was not a definitive reason for the bridge failure," he said.

"There were a number of things that may have contributed, but no definitive reason other than obviously very high floodwater."

Instead, his report outlines five options to replace the bridge, ranging from a "do minimum" approach, with no new bridge and permanent detours, to a cycle bridge only, costing $800,000, or a new structure.

A new bridge would cost up to  $1.6million, while the recommended option of a "new heritage bridge" would cost up to $2 million.

A like-for-like replacement of the old heritage bridge, costing $1.5 million, is not recommended as it carries "significant risk", the report says.

That includes a risk the replacement "would have the same issues ... that the previous bridge did".

When consenting, design and other peripheral costs are included, the total bill for the recommended option rises to $2.5 million.

The New Zealand Transport Agency has confirmed it will cover 76% of the cost, meaning the council’s share would be about $600,000 and come from existing budgets.

The new heritage structure could make use of the original bridge’s stonework and other non-structural materials, although structural components would need to be new, Mr Saunders said.

It would also be designed to accommodate predicted flood levels for the future.

If confirmed by councillors today, construction of the bridge could begin in the 2018-19 financial year. 

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